Interface Stability of Ti(Sil−yGey)2 and Si1−x Gex Alloys

1995 ◽  
Vol 402 ◽  
Author(s):  
D. B. Aldrich ◽  
F. M. D'Heurle ◽  
D. E. Sayers ◽  
R. J. Nemanich
Keyword(s):  
Solid Solution ◽  
Solid Phase ◽  
Equilibrium Diagram ◽  
Two Phase ◽  
Germanium Content ◽  
Tie Lines ◽  
Two Phases ◽  
Silicon And Germanium ◽  
Classical Thermodynamics ◽  
Tie Line

AbstractThe stability of C54 Ti(Si1−yGey)2 films in contact with Si1−xGex substrates was investigated. The titanium germanosilicide films were formed from the Ti − Si1−xGex solid phase metallization reaction. It was observed that Ti(Si1−yGey) 2 initially forms with the same germanium content as the Si1−x Gex substrate (i.e., y = x). Following the initial formation of TiM2 (M = Sil−yGey), silicon and germanium from the substrate diffuse into the TiM2 layer, the composition of the TiM2 changes, and Si1−z Gez precipitates form along the TiM2 grain boundaries. The germanium content of the Ti(Sil−y Gey)2 decreases, and the Sil−z Gez precipitates are germanium rich such that y < x < z. This instability of the TiM2 film and the dynamics of the germanium segregation were examined using the Ti-Si-Ge ternary equilibrium diagram. The relevant region of the ternary diagram is the two phase domain limited by a Si-Ge solid solution and a TiSi2 − TiGe2 solid solution. In this study first approximation Ti(Sil−y Gey)2 -to- Sil−xGex tie lines were calculated on the basis of classical thermodynamics. The tie line calculations indicate that for C54 Ti(Sil−yGey)2 to be stable in contact with Sil−xGex, the compositions of the two phases in equilibrium must be such that y < x. The specific compositions of the two phases in equilibrium depend on the temperature and the relative quantities of the two phases. The dynamic processes by which the Ti(Si1−yGey)2/Si1−x. Gex, system progresses from the as-formed state (y = x) to the equilibrium state (y < x) can be predicted using the tie line calculations.

Kinematic and Dynamic Parameters of a Liquid-Solid Pipe Flow Using DPIV∕Accelerometry

2007 ◽  
Vol 129 (11) ◽  
pp. 1415-1421 ◽  
Author(s):  
Joseph Borowsky ◽  
Timothy Wei
Keyword(s):  
Pipe Flow ◽  
Solid Phase ◽  
Fluid Phase ◽  
Central Moment ◽  
Steady Flows ◽  
Dynamic Parameters ◽  
Two Phase ◽  
Turbulence Structures ◽  
Two Phases ◽  
Flat Profile

An experimental investigation of a two-phase pipe flow was undertaken to study kinematic and dynamic parameters of the fluid and solid phases. To accomplish this, a two-color digital particle image velocimetry and accelerometry (DPIV∕DPIA) methodology was used to measure velocity and acceleration fields of the fluid phase and solid phase simultaneously. The simultaneous, two-color DPIV∕DPIA measurements provided information on the changing characteristics of two-phase flow kinematic and dynamic quantities. Analysis of kinematic terms indicated that turbulence was suppressed due to the presence of the solid phase. Dynamic considerations focused on the second and third central moments of temporal acceleration for both phases. For the condition studied, the distribution across the tube of the second central moment of acceleration indicated a higher value for the solid phase than the fluid phase; both phases had increased values near the wall. The third central moment statistic of acceleration showed a variation between the two phases with the fluid phase having an oscillatory-type profile across the tube and the solid phase having a fairly flat profile. The differences in second and third central moment profiles between the two phases are attributed to the inertia of each particle type and its response to turbulence structures. Analysis of acceleration statistics provides another approach to characterize flow fields and gives some insight into the flow structures, even for steady flows.

Phase Transformation in Granular Alloys of Cu2S-Ni3S2-Na2S System

2014 ◽  
Vol 353 ◽  
pp. 263-268
Author(s):  
Evgeny N. Selivanov ◽  
L.Yu. Udoeva ◽  
N.I. Selmenskich
Keyword(s):  
Solid Solution ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Hydrometallurgical Processing ◽  
Degree Of Separation ◽  
Large Particles ◽  
Dendrite Solidification ◽  
Sulfide Melt ◽  
Two Phases ◽  
Granular Alloys

The effect of Na2S on the phase composition and microstructure of tempered Cu2S-Ni3S2 alloys was studied by X-ray diffraction, optical microscopy and electron probe microanalysis (EPMA). It was found that quick crystallization of the sulfide melt leads to separation into two phases - Ni3S2 and a solid solution of Cu2S with Na2Cu4S5, moreover, nickel is concentrated in large particles and copper – in small ones. In contrast to the fine dendrite solidification of granular Cu2S-Ni3S2 alloys, in the ternary system there is a well-defined two-phase microstructure with rounded borders of the interface. Friability and a low microhardness of Cu2S - Na2Cu4S5 solid solution provide an autodecomposition of the sulfides melt by quenching into water (granulation). The degree of separation of copper and nickel depends on the overheating temperature and a quantity of Na2S in melt. The results can be used to hydrometallurgical processing of copper-nickel convert matt.

Liquid-Liquid Equilibria for Acetone + Several Citrates Aqueous Two-Phase Systems at Different Temperatures

2012 ◽  
Vol 549 ◽  
pp. 30-35
Author(s):  
Shi Ping Hu ◽  
Juan Han ◽  
Yong Sheng Yan ◽  
Yu Tao Hu
Keyword(s):  
Ternary Systems ◽  
Data Fitting ◽  
Potassium Citrate ◽  
Liquid Equilibrium ◽  
Two Phase ◽  
Different Temperatures ◽  
Tie Lines ◽  
Aqueous Two Phase Systems ◽  
Phase Systems ◽  
Tie Line

Liquid-liquid equilibria for the three kinds of the ternary systems acetone + ammonium, sodium or potassium citrate + water have been determined at T= (273.15, 283.15, and 298.15) K. Binodal curves, tie-lines, and integrated phase diagrams for the ternary systems are given. The data of the experimental bimodal curve are described with a four-parameter equation. The result also shows the temperature has little influence on the liquid-liquid equilibrium within the investigated range. The tie-line data calculated according to the bimodal data fitting equation and the lever arm rule were satisfactorily described by using the Othmer-Tobias and Bancroft equations, and the result conform the reliability of the calculation method and corresponding tie-line data.

Mechanism of Alcohol Displacement of Oil from Porous Media

1961 ◽  
Vol 1 (03) ◽  
pp. 195-212 ◽  
Author(s):  
J.J. Taber ◽  
I.S.K. Kamath ◽  
Ronald L. Reed
Keyword(s):  
Phase Behavior ◽  
Calcium Chloride ◽  
Solid Phase ◽  
Equilibrium Phase ◽  
Water System ◽  
Commercial Application ◽  
Practical Result ◽  
Immiscible Mixture ◽  
Two Phases ◽  
Tie Line

Abstract Alcohol floods of consolidated sandstone cores have shown the process to be strongly dependent on the phase behavior of the particular alcohol-oil-water system used. This means that in many cases the mechanism does not conform to the idea of a piston-like displacement. Instead, it is found that by changing the alcohol it is possible to change the relative velocities of the oil and water and, in fact, the entire mechanism of the process. The effects of rate, viscosity, initial saturation, distance travelled and hysteresis of relative permeability on the alcohol flooding mechanism are discussed. Introduction Reasons for interest in the use of alcohol to miscibly displace oil and water from a porous medium appear in the existing literature. The mechanism of the displacement has been considered and the apparent implications formulated into a theory which presumably would enable one to predict the essential features of the process. Unfortunately, most of the reported experiments have been performed with unconsolidated or artificially consolidated sands. With these systems some of the noteworthy facets of the process are obscured and resulting data appear uncertain. It is the purpose of this paper to show how the use of consolidated sandstones has led to revision of the mechanism and, hence, the theory of alcohol flooding. The practical result is increased pessimism toward the possibilities of commercial application of the simplest form of the alcohol-slug process. However elucidation of the mechanism has made it possible to define the essential characteristics of a system of slugs which will behave in a nearly piston-like fashion and, thus, yield the best possible result. Equilibrium Phase Behavior Fig. 1 is a diagram of the ternary system isopropyl alcohol (IPA)-Soltrol-calcium chloride brine. Brine was used to prevent plugging of the core and calcium chloride was used because sodium chloride brine exhibits a solid phase with Soltrol and IPA. If alcohol is added in increments to the immiscible mixture of water and oil represented by Point A, the path followed by the successively equilibrated samples will be on the Line ABC and pass from the immiscible region to the miscible region by crossing the binodal curve at B. Consider the intersection D of this path with the tie Line EF. The quantity of oleic phase is proportional to the Segment ED and the quantity of the aqueous phase is proportional to DF. Compositions of the two phases are specified by Points E and F. It is clear that in the case shown the oleic phase is diminishing and entirely disappears when miscibility is achieved.

Tie Simplex Based Parameterization for Compositional Reservoir Simulation

2008 ◽  
Author(s):  
Denis Voskov ◽  
Hamdi A. Tchelepi
Keyword(s):  
Method Of Characteristics ◽  
Flow Simulation ◽  
Deep Understanding ◽  
General Purpose ◽  
Two Phase ◽  
Compositional Flow ◽  
Reservoir Flow ◽  
Tie Lines ◽  
Solution Route ◽  
Tie Line

In this work, we generalize the Compositional Space Parameterization (CSP) approach, which was originally developed for compositional two-phase reservoir flow simulation. Tie-line based parameterization methods [1]–[3] were motivated by insights obtained from MOC (Method of Characteristics) theory. The MOC based analytical theory [4] has provided deep understanding of the interactions between thermodynamics and flow. In our adaptive framework, tie-lines are used to represent the solution route of multi-component multiphase displacements. The tie-line information is used as a preconditioner for EOS computations in general-purpose compositional flow simulation.

Study on the Application of the Tie-Line-Table-Look-Up-Based Methods to Flash Calculations in Compositional Simulations

SPE Journal ◽  
2013 ◽  
Vol 18 (05) ◽  
pp. 932-942 ◽  
Author(s):  
Wei Yan ◽  
Abdelkrim Belkadi ◽  
Michael L. Michelsen ◽  
Erling H. Stenby
Keyword(s):  
Computation Time ◽  
Phase Region ◽  
General Situation ◽  
Shadow Region ◽  
Two Phase ◽  
Feed Composition ◽  
Simulation Speed ◽  
Recent Approach ◽  
Tie Lines ◽  
Tie Line

Summary Flash calculation can be a time-consuming part in compositional reservoir simulations, and several approaches have been proposed to speed it up. One recent approach is the shadow-region method that reduces the computation time mainly by skipping stability analysis for a large portion of the compositions in the single-phase region. In the two-phase region, a highly efficient Newton-Raphson algorithm can be used with the initial estimates from the previous step. Another approach is the compositional-space adaptive-tabulation (CSAT) approach, which is based on tie-line table look-up (TTL). It saves computation time by replacing rigorous phase-equilibrium calculations with the stored results in a tie-line table whenever the new feed composition is on one of the stored tie-lines within a certain tolerance. In this study, a modified version of CSAT, named the TTL method, has been proposed to investigate if approximation by looking up a tie-line table can save flash-computation time in the two-phase region. The number of tie-lines stored for comparison and the tolerance set for accepting the feed composition are the key parameters in this method because they will influence the simulation speed and the accuracy of simulation results. We also proposed the tie-line distance-based approximation (TDBA) method, an alternative method to TTL, to obtain approximate flash results in the two-phase region. The method uses the distance to a previous tie-line in the same grid-block to determine whether the approximation should be made. Comparison between the shadow-region approach and the approximation approach, including TTL and TDBA, has been made with a slimtube simulator by which the simulation temperature and the simulation pressure are set constant. It is shown that TDBA can significantly improve the speed in the two-phase region. In contrast, TTL, even with a precalculated tie-line table, is not so advantageous compared with an efficient implementation of rigorous flash. Furthermore, we implemented TDBA in a compositional streamline simulator to apply TDBA to scenarios with pressure variation across the reservoir. We also discussed how to extend TDBA to the general situation in which pressures in grid-blocks are updated dynamically.

Reaction Sintering of β-Si3N4/α'-Sialon Ceramics

1992 ◽  
Vol 287 ◽  
Author(s):  
S. Boskovic ◽  
K.J. Lee ◽  
T.Y. Tien
Keyword(s):  
Solid Solution ◽  
Applied Pressure ◽  
Phase Region ◽  
Reaction Sintering ◽  
Two Phase ◽  
Sintering Aid ◽  
Third Phase ◽  
Solid Solution Region ◽  
Tie Lines ◽  
Solution Region

ABSTRACTCompositions in the α'-SiAlON-√-Si3N4 solid solution region in the system Si,Al,Y/N,O which contained a third phase as a sintering aid were prepared. Mixtures of starting materials were reaction sintered to full densities without applied pressure. Phases were identified and lattice parameters of β' and √ph ases were measured and compared with standards. The results were used to construct β'-SiAION-√-Si3N4 solidsolution tie lines in the two phase region. As expected, the specimens with a higher β'-SiAION content showed higher hardness and lower toughness values.

scholarly journals The equilibrium and lattice-spacing relations in the system magnesium-cadmium

1940 ◽  
Vol 174 (959) ◽  
pp. 471-486 ◽  
Keyword(s):  
Solid Solution ◽  
Solid Solutions ◽  
Low Temperatures ◽  
Equilibrium Diagram ◽  
Continuous Solid Solution ◽  
Phase Region ◽  
Metastable Equilibrium ◽  
Careful Examination ◽  
Two Phase ◽  
Fixed Composition

The alloys of magnesium and cadmium are of great interest, since both metals have the same valency, and almost the same atomic volume, but the axial ratios of their close-packed hexagonal structures differ markedly, being 1.885(2) for cadmium, and 1.6237 for magnesium. The equilibrium diagram of the system has always attracted great interest, and very conflicting results have been obtained by different investigators. The earlier investigations led to the conclusion that the liquidus and solidus curveswere very close together, and fell continuously from the melting point of magnesium to that of cadmium, so that, at the higher temperatures, a continuous solid solution was formed, which, at low temperatures, under­went a transformation in the region of 50 atomic % of cadmium, owing to the supposed existence of a compound MgCd. The work of Hume-Rothery and Rowell (1927) confirmed the existence of this transformation, and later work (Grube and Schiedt 1930; Dehlinger 1930; Riederer 1937) showed that this transformation corresponded to the formation of a superlattice based on the composition MgCd, and that at low temperatures two other super­lattices, based on the compositions MgCd 3 and Mg 3 Cd, were also formed. These low temperature transformations were securely established, and all investigations indicated the existence of wide solid solutions in both magnesium and cadmium, but the remainder of the system has been in great dispute. According to Hume-Rothery and Rowell, magnesium could hold approximately 60 atomic % of cadmium in solid solution, and cad­mium could dissolve approximately 24 atomic % of magnesium, whilst, between these two solid solutions, a compound MgCd 2 of fixed composition was formed by a peritectic reaction. Grube and Schiedt (1930) qualita­tively confirmed the limits of the primary solid solutions, but not the existence of the compound MgCd 2 , and, apart from the superlattice trans­formations, their equilibrium diagram showed the two primary solid solutions separated by a two-phase region. Dehlinger (1930) stated that his X-ray investigations confirmed the diagram of Grube and Schiedt, but a careful examination of his powder photographs shows that they are really inconclusive, since, with varying compositions, lines appear and disappear in a way which is consistent with the existence of MgCd 2 . Riederer (1937) concluded that the diagram of Hume-Rothery and Rowell represented stable equilibrium, and that of Grube and Schiedt metastable equilibrium. The present investigation has succeeded in explaining these apparent inconsistencies, and has also shown interesting relations between the two types of crystal structure, which may be interpreted in terms of the Brillouin zone theories.

Simulation of the Rheology of Semisolid Alloys by Using a Two-phase Flow Approach

2000 ◽  
Vol 652 ◽  
Author(s):  
A. Ludwig ◽  
M. Wu ◽  
T. Hofmeister
Keyword(s):  
Two Phase Flow ◽  
Solid Phase ◽  
Numerical Models ◽  
Flow Behavior ◽  
Phase Flow ◽  
Momentum Exchange ◽  
Two Phase ◽  
Semisolid Alloys ◽  
Dependent Flow ◽  
Two Phases

ABSTRACTSemisolid alloys exhibit a shear rate history dependent flow behavior. The increasing interest on numerical modeling of thixo-casting processes makes it quite important to understand the flow behavior of semisolids. Its apparent viscosity is the key parameter for the numerical models. In this paper a two phase approach is used to investigate the rheology of semisolid alloys. It is assumed that both, liquid and solid phase, can be regarded as inter-penetrating continua with its own viscosity. Thus, each phase is thought to behave as a Newtonian fluid. The simulation results show that the rheology of the two-phase flow is determined by the interaction between the solid and the liquid, i.e. the momentum exchange between the two phases. Non-Newtonian flow behavior of the solid-liquid mixture is predicted although both phases are considered as Newtonian fluids.

Analytical Solutions for Gas Displacements With Bifurcating Phase Behavior

SPE Journal ◽  
2014 ◽  
Vol 19 (05) ◽  
pp. 943-955 ◽  
Author(s):  
Saeid Khorsandi ◽  
Kaveh Ahmadi ◽  
Russell T. Johns
Keyword(s):  
Phase Behavior ◽  
Analytical Solutions ◽  
Phase Region ◽  
Co2 Injection ◽  
Two Phase ◽  
Complex Phase ◽  
Three Phase ◽  
Tie Lines ◽  
Tie Line ◽  
Composition Path

Summary Minimum miscibility pressure (MMP) is one of the most important parameters in the design of a successful gasflooding process. The most-reliable methods to calculate the MMP are based on slimtube experiments, 1D slimtube simulations, mixing-cell calculations, and the analytical methods known as the method of characteristics (MOC). The calculation of MMP by use of MOC is the fastest method because it relies solely on finding the key tie lines in the displacement path. The MOC method for MMP estimation in its current form assumes that the composition path is a series of shocks from one key tie line to the next. For some oils, however, these key tie lines do not control miscibility, and the MMP calculated by use of the key-tie line approach can be significantly in error. The error can be as high as 5,000 psia for heavier oils or CO2 displacements at low temperature in which three-phase hydrocarbon regions can exist (L1–L2–V). At higher pressures, the two- or three-phase region can split (or bifurcate) into two separate two-phase regions (L1–L2 and L1–V regions). Thus, for the MMP calculation from MOC to be correct, we must calculate the entire composition path for this complex phase behavior, instead of relying on the shock assumption from one key tie line to the next. In this paper, the MOC-composition route is developed completely for the bifurcating phase-behavior displacement for pure CO2 injection by use of a simplified pseudoternary system that is analogous to the complex phase behavior observed for several real displacements with CO2. We develop the MOC analytical solutions by honoring all constraints required for a unique solution—velocity, mass balance, entropy, and solution continuity. The results show that a combination of shocks and rarefaction waves exists along the nontie-line path, unlike previous MOC solutions reported to date. We show that by considering the entire composition path, not just the key tie lines, the calculated MMP agrees with the mixing-cell method. We also show that, in this complex ternary displacement, the displacement mechanism has features of a both condensing and vaporizing (C/V) drive, which was thought to be possible only for gasfloods with four or more components. For pure CO2 injection, the solution also becomes discontinuous for oils that lie on the tie line envelope curve. Finally, we show that shock paths within the two-phase region are generally curved in composition space and that there is no MMP for some oil compositions considered in the displacements by CO2. Recovery can be large even though the MMP is not reached.

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